Again it's a complex field. There's a certain amount of truth in that, because if Canada has the highest rates then you take the deduction in Canada. But the problem is that with a double-dip structure you get such an incentive to borrow that you borrow more. I've seen layers where you can get a triple deduction, and in effect the more you borrow the more money you can make.
That's artificial. It distorts the economy and induces people to borrow money they wouldn't otherwise borrow. So it's not quite true that it wouldn't have any effect on the Canadian tax system. But if you reduce it down to a single deduction, that may wind up in Canada and give you much the same effect as you have now.
I put it to you that it's wrong economics to allow the double-dip to proceed, because it simply distorts international investment.